Shigella is very contagious. People get infected with shigella when they come in contact with and swallow small amounts of bacteria from the stool of a person who is infected with shigella. For example, this can happen in a child care setting when staff members don't wash their hands well enough after changing diapers or helping toddlers with toilet training. Shigella bacteria can also be passed in infected food or by drinking or swimming in unsafe water. Children under age 5 are most likely to get shigella infection, but it can occur at any age. A mild case usually clears up on its own within a week. When treatment is needed, doctors generally prescribe antibiotics.

Signs and symptoms of shigella infection usually begin a day or two after contact with shigella. But it may take up to a week to develop. Signs and symptoms may include:

• Diarrhea (often containing blood or mucus)
• Stomach pain or cramps
• Fever
• Nausea or vomiting

Causes:

Infection occurs when you accidentally swallow shigella bacteria. This can happen when you:

• Touch your mouth: Direct person-to-person contact is the most common way the disease is spread. For example, if you don't wash your hands well after changing the diaper of a child who has shigella infection, you may become infected yourself.
• Eat contaminated food: Infected people who handle food can spread the bacteria to people who eat the food. Food can also become infected with shigella bacteria if it grows in a field that contains sewage.
• Swallow contaminated water: Water may become infected with shigella bacteria either from sewage or from a person with shigella infection swimming in it.

Risk factors:

• Being a child: Children under age 5 are most likely to get shigella infection. But shigella can infect people of any age.
• Living in group housing or participating in group activities: Close contact with other people spreads the bacteria from person to person. Shigella outbreaks are more common in child care centers, community wading pools, nursing homes, jails and military barracks.
• Living or traveling in areas that lack sanitation: People who live or travel in developing countries are more likely to get shigella infection.
• Being a man who has sex with men: Men who have sex with men are at higher risk of shigella infection because of direct or indirect oral-anal contact during sexual activity.

Complications:

• Dehydration: Constant diarrhea can cause dehydration. Signs and symptoms include lightheadedness, dizziness, lack of tears in children, sunken eyes and dry diapers. Severe dehydration can lead to shock and death.
• Rectal prolapse: In this condition, straining during bowel movements or inflammation of the large intestine may cause the mucous membrane or lining of the rectum to move out through the anus.
• Hemolytic uremic syndrome: This rare complication of shigella, more commonly caused by a type of E. coli bacteria than by shigella bacteria, can lead to a low red blood cell count (hemolytic anemia), low platelet count (thrombocytopenia) and acute kidney failure.

Prevention:

• Wash hands with soap and water for at least 20 seconds frequently
• Watch small children when they wash their hands
• Throw away soiled diapers properly

Media Contact
David Paul
Managing Editor
Journal of Infectious Diseases and Diagnosis